This invention relates to a chain incorporating rotating tool pots, for use in the tool magazine of an automatic tool exchange apparatus.
A rotating tool pot chain has a large number of tool pots equipped with tools, and travels in a circulating path in a tool magazine. In operation, the chain stops to position a particular tool pot at a tool exchange position along the circulating path in the tool magazine. At the tool exchange position, the tool pot rotates on the chain, and a tool is attached to, or detached from, the tool pot in a tool exchange operation.
A conventional rotating tool pot chain is disclosed in Japanese Utility Model Publication No. 63-48364, and is depicted in FIGS. 4 and 5 of this application, which are, respectively, a front elevational view, partly in cross-section, of the rotating tool pot chain, and a right side elevational view thereof.
The rotating tool pot chain 1 shown in FIGS. 4 and 5 consists of a chain 2 and a tool pot 12. In the chain 2, a connection pin 6 connects inner link plates 3, which interpolate rollers 5, and a pair of outer link plates 4 and 4xe2x80x2. One outer link plate 4 is laterally bent approximately perpendicularly to form a horizontal portion 7, and upwardly bent shaft supports 8 are formed on horizontal portion 7. The upwardly bent shaft supports 8 are hinged to brackets 13 provided on the back portion of the main body 15 of the tool pot 12 by a pin 14, so that the tool pot 12 is freely rotatable about the pin 14. A support 9, that holds the main body 15 of the tool pot 12, is formed on the other outer link plate 4xe2x80x2. A positioning roller 1 is freely rotatable about a pin 17 at the upper ends of the brackets 13.
When the chain 1 stops, positioning a tool pot at a tool exchange position along the circulating path in the tool magazine, a member (not shown) presses the roller 16, causing the tool pot 12 to rotate through an angle of approximately 90 degrees about pin 14. Then, in a tool exchange operation, a tool (not shown) is attached to, or detached from, the tool pot 12.
Several problems have been encountered in the operation of the rotating tool pot chain shown in FIGS. 4 and 5.
The center of the tool pot 12 is remote from the connection pins 6 of the chain 2 and therefore not on the pitch line of the chain. Consequently, the chain 1 can only be bent in one direction, i.e., the direction in which the tool pots separate from one another. It cannot be bent in the reverse direction because the tool pots would collide with one another. The inability of the chain to be bent in both directions limits the ways in which the tool magazine can be laid out.
The pin 14, which is the fulcrum about which the tool pot 12 rotates, and the positioning roller 16, are both located above the connection pins 6. The pin 14 should be close to the connection pins, but this means that the fulcrum is below the center of the tool pot, and results in a large distance from the fulcrum to the tip portion of the main body 15 of the tool pot. The area swept by the tool pot 12 when the tool pot 12 rotates is accordingly large.
Since pin 14, the fulcrum about which the tool pot 12 rotates, is located at the upper end of the outer link plate 4, and is remote from the pitch line of the chain 2, considerable vibration is transmitted from the chain to the tool pot 12. The vibration tends to cause the tool pot 12 to become unstable, and can cause a tool to drop from the tool pot.
The object of this invention is to solve the foregoing problems encountered with conventional rotating tool pot chains, and to provide a rotating tool pot chain that is capable of bending in both directions, that has tool pots arranged to sweep a small area as they rotate, and that is capable of holding the tool pots stably.
According to a first aspect of the invention, a rotating tool pot chain has tool pots attached to and carried by a chain comprising pairs of inner link plates and pairs of outer link plates arranged alternately along the length of the chain, and connection pins articulably connecting the pairs of inner link plates with the pairs of outer link plates. Each pair of inner link plates and each pair of outer link plates has an opening, the openings in the link plates of each pair of link plates forming tool pot receiving and storage areas. A fulcrum connects each said tool pot to a link plate of a pair of link plates for rotation of the tool pot about an axis parallel to the length of the chain. Each tool pot has a center, and the storage areas are positioned so that, when the tool pots are received in the storage areas, the centers of the tool pots are aligned with the connection pins along a chain pitch line passing through the centers of said connection pins.
According to a second aspect of the invention, at the tool exchange location along the chain path, each fulcrum is located at a level below the level of the chain pitch line, but preferably above the level of the bottoms of the tool pot storage areas.
By positioning the center of each tool pot storage area on the chain pitch line linking the centers of the adjacent connection pins, it is possible to bend the chain in both directions.
Furthermore, since the fulcrum about which the tool pot rotates is below the connection pins but above the bottoms of the tool pot storage areas, the area swept by the tool pot as it rotates is not large, and the tool pot is held stably on the chain.